package com.opensource.netty.redis.proxy.commons.algorithm;

import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;

import com.opensource.netty.redis.proxy.commons.algorithm.impl.support.SafeEncoder;


/**
 * hash 算法接口
 * @author liubing
 *
 */
public interface Hashing {
	
	public ThreadLocal<MessageDigest> md5Holder = new ThreadLocal<MessageDigest>();

    public static final Hashing MD5 = new Hashing() {
        public long hash(String key) {
            return hash(SafeEncoder.encode(key));
        }

        public long hash(byte[] key) {
            try {
                if (md5Holder.get() == null) {
                    md5Holder.set(MessageDigest.getInstance("MD5"));
                }
            } catch (NoSuchAlgorithmException e) {
                throw new IllegalStateException("++++ no md5 algorythm found");
            }
            MessageDigest md5 = md5Holder.get();

            md5.reset();
            md5.update(key);
            byte[] bKey = md5.digest();
            long res = ((long) (bKey[3] & 0xFF) << 24)
                    | ((long) (bKey[2] & 0xFF) << 16)
                    | ((long) (bKey[1] & 0xFF) << 8) | (long) (bKey[0] & 0xFF);
            return res;
        }
    };

    public long hash(String key);

    public long hash(byte[] key);
    
}
